Triggering Of Reference Signals And Control Signaling

ABSTRACT

When triggering a user equipment (UE) to send a reference signal (SRS) the network configures the UE with multiple parameter sets, each having a timing indication. The UE&#39;s resource allocation grants multiple uplink (UL) subframes and identifies/selects one of those parameter sets. The timing indication of the selected set identifies one of the granted UL subframes, in one embodiment by counting only among the allocated/granted shortened UL subframes. This triggers the UE to send SRS in that identified shortened UL subframe. In one embodiment if no UL subframes in the grant are shortened this triggers the UE to send SRS in a subframe previous to all the allocated/granted multiple UL subframes. The same mechanism can be used to trigger feedback reports such as aperiodic channel state information or block ACK/NACK reports, where the different UL signaling being triggered is requested in the network&#39;s resource allocation to the UE.

TECHNOLOGICAL FIELD

The described invention relates to wireless communications, and moreparticularly to the triggering the sending of sounding reference signals(SRS) and/or aperiodic channel state information (A-CSI) reports and/orblock acknowledgement (block ACK/NACK) in a radio environment in which asingle grant of uplink radio resources grants a given user equipment(UE) multiple uplink subframes.

BACKGROUND

Acronyms used herein are listed below following the detaileddescription. Rel-13 LTE LAA (Licensed Assisted Access) provideslicensed-assisted access to unlicensed spectrum while coexisting withother technologies and fulfilling various regulatory requirements. Asused herein, licensed refers to licensed radio spectrum such as forexample conventional cellular band and unlicensed refers tolicense-exempt radio spectrum such as for example that used byconventional wireless local area networking utilizing various of theIEEE 802.11 radio protocols. In Rel-13 LAA, unlicensed spectrum isutilized to improve the LTE DL throughput. In this solution, one or moreLAA DL SCells may be configured to a UE as part of DL CA configuration,while the PCell needs to be on licensed spectrum.

Document RP-152272 by Ericsson and Huawei entitled New Work item onenhanced LAA for LTE [3GPP TSG RAN Meeting #70; Sitges, Spain; 7-10 Dec.2015] introduces unlicensed band UL operation, and includes somediscussion on SRS operation in LAA.

Relatedly, the MulteFire Alliance is developing specifications forMulteFire technology which is to be a stand-alone unlicensed bandoperation (unlike LTE LAA which requires the assisting PCell to be inthe licensed band) in which one requirement is that the MulteFire ULsupports SRS. Generally the Multefire Alliance is proceeding by usingcertain building blocks from LTE LAA, and it is intending to also usebuilding blocks from Rel. 14 eLAA, as much as may be appropriate inorder to speed up the development of this LTE technology-basedstand-alone operation in the unlicensed bands.

UL sounding reference signal transmissions are an integral part of theLTE system operation. SRS in LTE is used for UL link adaptation(including spatial and multiple-input-multiple-output (MIMO) linkadaptation) as well as for UL sounding based DL precoding and linkadaptation in the case of LTE TDD/FS 2 (Frame Structure 2) utilizingchannel reciprocity. SRS operation for unlicensed bands is beingdeveloped to have similar use cases.

UL SRSs are sent by the UE in certain specified locations of the radioframe. In relevant part for LTE, that is SRS with the trigger type 1,the UE learns when it should transmit an SRS jointly from the higherlayer configured parameters and PDCCH which carries the UE's schedulingallocation. More specifically, the UE learns when it should transmit SRSfrom its grant of UL resources that it receives in the PDCCH combinedwith higher layer configuration of periodicity and timing offset of SRSopportunities in relation to the subframe number. But for unlicensedband operation in LTE LAA and in MulteFire a single PDCCH may grant to agiven UE multiple UL subframes. To the inventors' knowledge, to dateneither LTE LAA nor MulteFire has dealt with the issue of SRStransmissions where a single resource grant gives allocation formultiple UL subframes.

Typically it is not useful for the network to receive an SRS in each ofthose multiple granted UL subframes since generally the channelconditions across those at least some of those multiple UL subframeswould be coherent and a single SRS could adequately represent thechannel across all those channel-coherent subframes. If the UE were toalways send an SRS in each of those multiple coherent UL subframes allbut one of those SRSs would generally represent wasted signaling. At thesame time a multiple UL grant in a single PDCCH is generally given tohigh-traffic UEs, so abstaining completely from receiving SRSs fromthose particular UEs in those scheduling events would tend to reducethroughput efficiency (by not having precise channel soundings) on thebusiest connections. What is needed in the art is a way for the networkto instruct or otherwise control the UE to send SRS in only selectedones (if any) of the multiple UL subframes granted in a single PDCCH,and to do so in an efficient way that does not add too much to thecontrol signaling overhead on the unlicensed band. As will be describedbelow, the solution herein for triggering the UE to send SRS works quitewell also for triggering the UE to send aperiodic channel stateinformation (CSI) reports which give the network information on qualityof the UE's downlink channel, or block ACK/NACK.

SUMMARY

In a first aspect of these teachings there is a method for transmittinga reference signal and/or a channel state information (CSI) reportand/or a block acknowledgement. In this aspect the method comprises a)receiving a configuration of multiple parameter sets each set includinga timing indication; b) receiving a grant that allocates multiple uplinksubframes; c) based on the grant, determining which of the multipleallocated uplink subframes are shortened such that uplink transmissionis prohibited in only a portion thereof; d) determining from the grantthat a reference signal and/or CSI report and/or block acknowledgementis requested; e) determining from the grant a selected one of themultiple parameter sets; f) identifying one uplink subframe based on thedetermination which of the multiple allocated uplink subframes areshortened; and g) transmitting the reference signal and/or the CSIreport and/or block acknowledgement as requested by the grant in theidentified uplink subframe.

In a second aspect of these teachings there is a computer readablememory storing computer program code that when executed by one or moreprocessors of a user equipment cause the user equipment to perform atthe above method.

In a third aspect of these teachings there is an apparatus comprising atleast one processor, and at least one memory storing computer programcode, which together are all configured to cause a user equipment (UE)to transmit a reference signal and/or a or channel state information(CSI) report and/or a block acknowledgement. More specifically, they areconfigured to cause the UE to at least: in response to receiving aconfiguration of multiple parameter sets each set including a timingindication and a grant that allocates multiple uplink subframes,determine based on the grant which of the multiple allocated uplinksubframes are shortened such that uplink transmission is prohibited inonly a portion thereof; determine from the grant that a reference signaland/or CSI report and/or block acknowledgement is requested; determinefrom the grant a selected one of the multiple parameter sets; identifyone uplink subframe based on the determination which of the multipleallocated uplink subframes are shortened; and transmit the referencesignal and/or the CSI report and/or block acknowledgement as requestedby the grant in the identified uplink subframe.

In a fourth aspect of these teachings there is a method for triggeringtransmission of a reference signal and/or a channel state information(CSI) report and/or a block acknowledgement. In this aspect the methodcomprises: a) transmitting to a user equipment (UE) a configuration ofmultiple parameter sets each set including a timing indication; b)determining multiple uplink subframes to be scheduled to a UE; c)identifying one uplink subframe in which the UE is to transmit areference signal and/or a CSI report and/or block acknowledgement; d)selecting one of the multiple parameter sets, wherein for the case inwhich at least one of the multiple uplink subframes is shortened suchthat uplink transmission is prohibited in only a portion thereof thetiming indication of the selected parameter set indicates the identifiedone uplink subframe from among the multiple uplink subframes; and e)transmitting to the UE a grant that schedules the UE for the multipleuplink subframes and that triggers the UE to transmit a reference signaland/or a CSI report and/or block acknowledgement, the grant furtheridentifying the selected parameter set and which if any of the multipleuplink subframes are shortened.

In a fifth aspect of these teachings there is a computer readable memorystoring computer program code that when executed by one or moreprocessors of a radio access node cause the radio access node to performthe method according to the above fourth aspect of these teachings.

And in a sixth aspect of these teachings there is apparatus comprisingat least one processor, and at least one memory storing computer programcode, which together are all configured to cause a radio access node totrigger transmission of a reference signal and/or a channel stateinformation (CSI) report and/or a block acknowledgement. Morespecifically, they are configured to cause the radio access node to atleast: transmit to a user equipment (UE) a configuration of multipleparameter sets each set including a timing indication; determinemultiple uplink subframes to be scheduled to a UE; identify one uplinksubframe in which the UE is to transmit a reference signal and/or a CSIreport and/or block acknowledgement; select one of the multipleparameter sets, wherein for the case in which at least one of themultiple uplink subframes is shortened such that uplink transmission isprohibited in only a portion thereof the timing indication of theselected parameter set indicates the identified one uplink subframe; andtransmit to the UE a grant that schedules the UE for the multiple uplinksubframes and that triggers the UE to transmit a reference signal and/ora CSI report and/or block acknowledgement, the grant further identifyingthe selected parameter set and which if any of the multiple uplinksubframes are shortened.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram illustrating an example of two radiocommunication devices that may be used to implement certain embodimentsof these teachings may be practiced.

FIG. 1B is a schematic diagram showing a PDCCH, granted UL subframes,and symbol positions within a single subframe that are relevant to theexamples herein.

FIG. 2 is a schematic diagram of multiple granted UL subframes grantedin a single grant according to a first embodiment in which no cyclic ormodulo operation is applicable for triggering the UE to send SRS.

FIG. 3 is a schematic diagram similar to FIG. 2 but according to asecond embodiment in which cyclic or modulo operation is utilized totrigger the UE to send SRS.

FIGS. 4A-B are process flow diagrams summarizing certain of the aboveteachings from the perspective of the UE and from the perspective of theserving network radio access node, respectively.

FIG. 5 is a high level schematic block diagram illustrating certainapparatus/devices that are suitable for practicing certain of theseteachings.

DETAILED DESCRIPTION

Certain of the examples below detail a triggering mechanism for SRStransmission for unlicensed band operation, specifically consideringmulti-subframe grant UL scheduling operation. While the LTE terminologyis utilized for improved clarity in describing exactly how theseexamples might work, the LTE radio access technology is not a limitingfactor in the broader teachings herein so the LTE names such as PDCCHand PUSCH, number of symbols per LTE subframe, and the like are notlimiting either.

For the reader not familiar with these particulars, following is asummary of certain agreements in LTE LAA/enhanced LAA concerning SRSs,as a background for a better understanding of the inventors' SRStriggering mechanisms that are more fully detailed in the belowexamples. For Rel-14, it has been agreed that SRS for eLAA is to betransmitted in last symbol of UL subframe, and further agreed that SRSfor eLAA is to use the waveform of licensed band LTE transmitted overthe (almost) full UL bandwidth. In the case of 20 MHz this full eLAA ULbandwidth corresponds to 100 UL PRBs and SRS bandwidth may correspond to96 PRBs. Frequency-selective, narrowband SAS transmission is riotsupported for eLAA (though it is supported in licensed band LTE SRS).

Further, several other agreements came out of the April 2016 RAN1Meeting #84bis, namely:

-   -   SRS, if present in a UL subframe, is transmitted at the end of        the subframe    -   Only wideband SRS transmission in supported in eLAA        -   The existing max number of SRS RBs for a given system            bandwidth is the baseline            -   It is for further study whether or not to extend/shift                to # of RBs >max # PRBs in the legacy case    -   One working assumption is that SRS is based on a legacy comb        structure        -   As a baseline, comb=2 and 4        -   It is for further study whether or not support different            comb value(s)

FIG. 1A is a schematic diagram of two communication devices that aresuitable for implementing embodiments of these teachings. A servingradio access node 20 represents the network side of the wireless dividethat sends the resource allocation grant downlink and which alsotriggers the SRSs. FIG. 1A also shows a user equipment UE 10 whichrepresents the mobile terminal side that sends the SRSs uplink (and alsosends its aperiodic CQI reports that inform the network of the downlinkchannel conditions seen by the UE 10). There may be further UEs in theaccess node's cell but for purposes of this description those othersoperate similar to the illustrated arid described UE 10 with respect tothe different signaling they receive from the network. While the radioaccess node 20 in the examples below is referred to as an eNB, this isnot a conventional LTE eNB in that the signaling described herein is onunlicensed spectrum and also the specific signaling described below isnot conventional LTE signaling.

FIG. 1B is a schematic diagram showing an UL grant on the DL controlchannel 110 (more generically, a resource allocation or resource grant),multiple UL subframes 120 a-d which are granted by that single PDCCH,and the symbols in an LTE subframe such as in each of those granted ULsubframes 120 a-d. LTE LAA only supports the ‘normal’ length cyclicprefix (CP) and thus the granted UL subframes 120 a-d in LTE LAA contain14 OFDM symbols or 14 SC-FDMA symbols, which as conventional are indexedfrom #0 to #13 such that the symbol in the first-in-time position of thesubframe is position #0 (denoted symb0 in FIG. 1B), and so forth for theother symbol positions through the last position #13 of the subframe.3GPP as well as the MulteFire Alliance has agreed to support such ULmulti-subframe scheduling with a single UL grant. With this operation, asingle UL grant 110 is able to schedule several UL subframes in order toreduce the (DL) control load and to enable scheduling of more than asingle UL subframe from a single DL subframe. This is seen to be mostuseful in the case of UL heavy traffic, and related UL heavy UL/DLresource partitioning of the unlicensed band carrier.

In order to enable SRS transmission in the last symbol of a subframe(symbol #13 of an UL subframe 120 a-d), the UE cannot transmit a PUSCHin the last symbol in any subframe where any other UE is transmittingSRS. For a UE with its own SRS transmission this is straightforward, butit is important to understand that in any given subframe, if one LIE istransmitting SRS then no other UEs in the cell can transmit PUSCH in thesame symbol position as that other UE's SRS transmission, even if thoseother UEs are not transmitting their own SRS.

This gives rise to the need for the radio network to signal if a PUSCHtransmission in a granted UL subframe should not include PUSCH in symbolposition #13 even if the network is not requesting that UE to transmitSRS itself. This is consistent with an agreement already in 3GPP thatthat there is to be a dynamic indication for the last PUSCH symbol in asubframe. More specifically the April 2016 RAN1 Meeting #84bis resultedin the following further agreements, of which the second bullet is mostrelevant:

-   -   Dynamic signaling indicates whether PUSCH in a UL subframe is        transmitted from        -   Start of DFTS-OFDM symbol 0 or        -   Start of DFTS-OFDM symbol 1        -   It is for further study if PUSCH can be transmitted within            DFTS-OFDM symbol 0    -   Dynamic signaling indicates whether PUSCH in a UL subframe is        transmitted up to OFDM symbol 13 or OFDM symbol 12    -   Any combination of the above options can be enabled by the        dynamic signaling

The April 2016 RAN1 Meeting #84bis resulted in additional agreementsbelow, but note that the italicized bullet below indicates that the SRSrequest/triggering mechanism is still open for the multi-subframescheduling operation shown by example at FIG. 1B:

-   -   DCI format(s) to schedule PUSCH transmission in k<=N subframes        with single TB per subframe or two TBs per subframe        -   Value(s) of N is for further study        -   Value N is either semi-statically configured or hard-coded,            to be further decided    -   DCI format(s) will have the following scheduling information        types:        -   Type A: common to all the scheduled subframes (appearing            only once in a DCI)            -   carrier indicator, resource assignment, Cyclic shift for                DM RS and OCC index        -   Type B: subframe specific information (appearing N times for            N subframes scheduling)            -   NDI        -   It is for further study whether MCS is type A or type B        -   It is for further study whether HARQ process number and            redundancy version are type A or type B        -   It is for further study about details of scheduling timing            indication, and whether it's type A or type B        -   It is for further study whether Type C is to be applied only            to one of the scheduled subframes (appearing only once in a            DCI)            -   CSI request, SRS request, TPC        -   Note: there are maybe other information fields in DCI,.to be            decided later

Note that the DCI formats immediately above may not be a complete list,the allowed DCIs may depend on further discussions in 3GPP on resourceallocation for PUSCH. In LTE the DCI format refers to the format of thePDCCH.

Embodiments of these teachings concern triggering the UE to send SRS,taking the dynamic PUSCH allocation signaling into account. For the caseof a resource grant allocating only a single UL subframe the problem isnot very difficult; the SRS can be triggered for the single UL subframeor not as is the case for conventional LTE. But for the ease of amulti-subframe UL grant, a SRS request can apply to any one or more ofthe multiple UL scheduled subframes. For convenience assume the singleresource allocation grant allocates a number of k subframes, where k isan integer greater than one. Embodiments of these teachings as detailedfurther below provides efficient design of the SRS request/trigger,which is suitable for eLAA and/or MulteFire UL multi-subframescheduling. Similar principles can be applied also in other systems suchas 5G New Radio configured to operate according to rules defined forunlicensed band operation and/or multi-subframe scheduling.Specifically, the examples below consider how to efficiently indicate tothe UE in which of the allocated PUSCH subframes it should transmit theSRS while still providing sufficient flexibility. Note that theinvention assumes that unlike LTE on licensed band, there is nopre-configured set of subframes for potential SRS transmissions, meaningthat any subframe can potentially be dynamically triggered for SRStransmission. This can improve the resource efficiency and theflexibility on unlicensed band considering the listen-before-talkrequired before a transmission and limited transmission burst duration.

In one aspect embodiments of these teachings may be considered as acompact joint signaling of SRS timing as well as SRS transmissionconfiguration. This joint signaling is interpreted by the UE incombination with another dynamic signaling that indicates whether PUSCHtransmission in the last symbol of a subframe, that is, in symbol #13 ofthe given PUSCH subframe is allowed by this UE or not.

As a starting point assume that with a single UL multi-subframe grant,only a single SRS transmission can be requested of the UE, though thistransmission may be done with one or more antenna ports. This followsfrom the channel coherence assumptions noted in the background sectionabove; it is reasonable that channel conditions in the subframesbelonging to the same UL multi-subframe grant are highly correlated, andthus adequately represented by a single SRS from this UE.

In relevant part, firstly the UE is configured with a number J ofdifferent SRS parameter sets, where J is an integer greater than one. Inthe specific example below J=3 SRS parameter sets can be configured forthe UE; this is preferred for implementation with eLAA since it can besignaled with 2 bits and already conventional LTE in the licensed bandfor UL transmission mode (TM) 2 operation 2 bits are used for SRSsignaling. In other embodiments there may be J=7 SRS parameter sets,which can be implemented using 3 bits to signal the UE which SRSparameter set is active for a given multi-subframe UL grant.

In one embodiment the SRS parameter sets are configured for the UE usinghigher layer signaling, for example Radio Resource Control (RRC)signaling which is a higher logical layer than the physical PHY layerand the media access control MAC layer. Utilizing multiple SRS parametersets enables the network to increase the efficiency and flexibility ofthe SRS resource usage. Multiple UEs in the cell will typically beconfigured with the same SRS resources. The eNB selects the SRSresources depending on which UEs are triggered to send SRS.

Conventional LTE UL TM2 operation in the licensed band also uses SRSparameter sets but the parameter sets according to these teachingsdiffer in the following ways at least. A first such difference is thateach SRS parameter set according to these examples contains a timecomponent parameter that indicates in which UL subframe the SRS isrequested to be transmitted in relation to the first scheduled ULsubframe. In conventional LTE UL operation the SRS parameter set containparameters that indicate the periodicity and subframe offset forsubframes where the UE may transmit SRS. The timing is indicated inrelation to subframe number, i.e. relative to radio frame time. Due toflexibility of UL multi-subframe scheduling, it is desirable to have ahigh level of flexibility on the definition and application of the SRSparameter sets. Hence, the SRS subframe indication is done relative tothe scheduled subframes that end their PUSCH transmission with symbol12, and it is the other dynamic signaling from the network that tellsthe UE which PUSCH subframes the UE is restricted from sending PUSCH insymbol position #13. Typically, both dynamic signaling fields (i.e. SRStriggering and PUSCH shortening) are included in the same UL resourceallocation grant

Each parameter set relates to the x^(th) UL subframe within an UL SFgrant where the PUSCH is ending in symbol position #12; these are the‘shortened’ UL subframes. So for example some specific SRS requestapplies to the 1^(st), or to the 2^(nd), or to the 3^(rd), (etc.)scheduled PUSCH subframe ending in symbol 12. The value of x is one ofthe RRC configured parameters in each of the different SRS parametersets.

Some parameters of the conventional LTE SRS parameter sets, such as forexample SRS bandwidth (BW) and frequency position, might not be neededfor implementations of these teachings for unlicensed band deployments.For example and as mentioned above, only wideband SRS transmission issupported for conventional/licensed band 3GPP eLAA. This may beimplemented in a way that 3GPP eLAA solution does not contain relatedparameters in the RRC signalling. Another option is to keep the currentRRC signalling unchanged, and leave it up to the eNB to make theconfiguration according to 3GPP eLAA rules. It is also possible todefine valid parameter values for the eNB, when using current RRCsignalling.

The UL multi-subframe grant sent on. the unlicensed band contains a2-bit SRS trigger. As mentioned above, in other embodiments this may bea 3-bit trigger or some other number of bits, depending on how many SRSparameter sets there are in the list stored locally at the radio accessnode 20 and at the UE 10. 2-bits is preferred for ready adaptation ofthese teachings for eLAA LTE, so as to re-use the LTE triggeringmechanism for different SRS sets. For the case in which embodiments ofthese teachings adopt the LTE SRS parameter sets directly (but modifiedto include at least the timing parameter), the following bit values fromtable 8.1.1 at section 8.2 UE sounding procedure of 3GPP TS 36.213v13.1.1 can be used (section 8.2 of 3GPP 36.213 v 13.1.1 is herebyincorporated by reference as if re-stated herein):

SRS request values for trigger type 1 in DCI format 4 Value of SRSrequest field Description ‘00’ No type 1 SRS trigger ‘01’ The 1^(st) SRSparameter set configured by higher layers ‘10’ The 2^(nd) SRS parameterset configured by higher layers ‘11’ The 3^(rd) SRS parameter setconfigured by higher layers

Based on the 2-bit (or other numbers of bits) SRS triggering alone theUE is not able to identify the UL subframe for SRS transmission; the SRStriggering value only tells the UE which parameter set to select fromits parameter set list. The subframe of the multiple-granted ULsubframes in which the SRS transmission is triggered is only determinedwhen combining the indicated applicable SRS parameter set (and inparticular the value of the timing parameter x) together with theinformation on the PUSCH subframes ending with symbol 12 (e.g., thosePUSCH subframes in which PUSCH transmissions in symbol position #13 arebarred).

In one particular embodiment, the UE uses a modulo/cyclic operation fordetermining the SRS subframe from among the N multiple-granted ULsubframes; this increases the SRS request flexibility for a small numberof shortened PUSCH subframes. It should be noted that the number ofshortened PUSCH subframes may vary between consecutive multi-subframescheduling. Thanks to modulo/cyclic operation detailed further below thesolution described herein scales also to the case where the eNBschedules just one shortened PUSCH subframe among the k multiple-grantedUL subframes. This means that all SRS parameter sets may be availablefor the UE also in the case of just one shortened PUSCH subframe.

For the case in which UE is configured by the network to transmit SRSwith multiple antenna ports, the UE transmits its SRS from all of thoseconfigured antenna ports in the same UL subframe. Obviously, differentSRS parameter sets may relate to different shortened PUSCH subframesalso with multiple antenna ports. In another embodiment different MIMOprofiles can be configured for the UE for the different SRS parametersets. As an example of this, one SRS parameter set could be configuredwith single-antenna port SRS, whereas two other SRS parameter sets canbe configured with multi-antenna port SRS respectively.

As mentioned above, the timing and triggering mechanism can also be usedfor triggering the UE to send aperiodic CSI reports (A-CSI) and/or blockacknowledgement. A block acknowledgement comprises HARQ acknowledgements(or HARQ negative acknowledgements) for all relevant DL HARQ processesand is transmitted by the UE after receiving a trigger in the UL grantfrom the eNB for sending block ACK/NACK. The relevant DL HARQ processescould be all the DL HARQ processes, or all the DL HARQ processes in use,or some other subset of the DL HARQ processes. But the exact definitionof the relevant DL HARQ processes to be included, in the block ACK/NACKis out of the scope of this invention. Specifically, when a resourceallocation from the network grants multiple UL subframes to the UE andfurther triggers the UE to send an A-CSI and/or block ACK/NACK, theabove signaling mechanism can be used to identify to the UE which ofthose multiple-granted UL subframes in which to send its A-CSI reportand/or block ACK/NACK. When combined with SRS transmissions, the exactsame signaling bits can inform the UE which of those multiple-granted ULsubframes in which to transmit its SRS and/or A-CSI report and/or blockACK/NACK so that whichever of these transmissions are triggered by thegrant can be sent in the same UL subframe.

A-C SI report and/or block ACK/NACK is different from SRS in the sensethat the A-CSI report and/or block ACK/NACK do not have to be sent in ashortened PUSCH subframe. They can be sent in any scheduled subframe.While sharing the same signaling bits with SRS, an alternative approachis to interpret the bits differently for A-CSI report and/or blockACK/NACK. Instead of having the parameter x indicating the SRS subframerelative to the scheduled shortened PUSCH subframes, it can beinterpreted as an indication relative to all the scheduled PUSCHsubframes for A-CSI report and/or block ACK/NACK. In this case, thesignaling bits do not need to be interpreted jointly with theinformation on the shortened PUSCH subframes.

Given the difference between SRS and A-CSI report and/or block ACK/NACK,instead of sharing the same signaling bits, separate signaling bits canbe used for each of them, or any two of them can share the samesignaling bits, while the signaling mechanism still follow the sameprinciple as described. The parameter set that include the subframeindication can also be configured separately. For example, thetriggering bits for A-CSI already exist in the UL resource allocationgrant today, and it can be potentially reused or modified to alsoindicate the subframe.

The following summarizes the signaling mechanism and resulting actionsfrom the perspective of the UE 10, and represents a method fortransmitting SRS (or Aperiodic CSI reports or block acknowledgement)when UL multi-subframe scheduling is applied. Firstly the UE receives aSRS (and/or A-CSI and/or block acknowledgement) parameter setconfiguration that includes a timing indication. In the example abovethe configuration is sent to the UE using higher layer signaling such asvia the UE's RRC configuration in the cell. Further in the above examplethe timing indication is relative to the scheduled PUSCH subframes thatare shortened from the end (those in which PUSCH is not allowed forsymbol position #13).

Next, based on the UL multi-subframe grant the UE determines the ULsubframes where PUSCH transmission in symbol #13 is not allowed (i.e.shortened PUSCH subframes). Based on this same UL multi-subframe grantthe UE also determines if an SRS transmission is requested by thenetwork, and if SRS transmission is requested the UE further determinesfrom the UL multi-subframe grant which SRS parameter set is used (e.g.,the 2-bit or 3-bit value).

From this determined SRS parameter set the UE then determines a value ofthe parameter x, which indicates the shortened UL subframe in which SRSshould be transmitted relative to other shortened UL subframes allocatedby the grant. So for example the SRS parameter set identified by bitvalue “11” may have a parameter x=3 that tells the UE it is to transmitSRS in the 3^(rd) shortened UL subframe that was allocated by the grant,while the SRS parameter set identified by bit value “10” may have aparameter x=2 that tells the UE it is to transmit SRS in the 2^(nd)shortened UL subframe that was allocated by the grant (here, ‘shortened’means PUSCH transmission in symbol position #13 is prohibited for thatsubframe). For the embodiment below that utilizes a modulo operation thevalue of x does not directly count off the shortened UL subframes thatare allocated by the grant and the specific subframe for SRS is given bythe value for n as detailed immediately below. For clarity, the signaledparameter in the SRS parameter set is referred to as x and the specificshortened subframe for the SRS transmission is referred to as n, and soin the simplest non-modulo operation implementation n=x which is truefor the above example.

Now based on the determined UL subframes where PUSCH transmission insymbol #13 is not allowed, and the parameter x, the UE can easilydetermine the UL subframe for its SRS transmission. In a firstembodiment n=x or more generically the determination of the specific ULsubframe for SRS transmission does not entail any modulo operation, butin an alternative second embodiment this determining of the UL subframefor SRS transmission may include a modulo/cyclic operation. As anexample of the latter, where the SRS is to be transmitted in the n^(th)UL subframe that PUSCH transmission in symbol #13 is not allowed, thepositive integer n may be defined as n=mod(x, number of UL subframeswhere PUSCH transmission in symbol #13 is not allowed), where the valuefor x is given in the selected SRS parameter set and the number ofshortened UL subframes is given by the grant itself.

Now having identified the specific (shortened) UL subframe of themultiple-granted UL subframes, the UE then transmits SRS (and A-CSIreport if the grant also triggered A-CSI) in the determined UL subframefor SRS transmission. The other SRS parameters apart from the timingparameter that are also within the selected SRS parameter set (forexample, parameters to identify the SRS sequence, the IFDMA-comb, thecyclic shift, and so forth) are as configured for the determined SRSparameter set.

The above described method from the UE's perspective can also representfunctions executed by computer code of a software program tangiblystored on a computer readable memory for implementing these teachings,or functions to control operation of a UE as performed by one or moreprocessors in cooperation with one or more computer readable memoriesstoring software computer code.

Now are summarized the signaling mechanism and relevant actions from theperspective of the network such as the radio access node 20, andrepresents a method for triggering a UE to transmit SRS (or AperiodicCSI reports) when UL multi-subframe scheduling is applied. Firstly thenetwork transmits to the UE a SRS parameter set configuration includinga timing indication for a UE. As mentioned above in some embodimentsthis configuration is sent to the UE using higher layer signaling suchas the UE's RRC configuration. In the above example the timingindication is relative to the number of scheduled shortened PUSCHsubframes.

With the UE configured with the list of SRS parameter sets the networkdetermines multiple UL subframes to be scheduled to a UE, and of thosemultiple UL subframes it also determines those UL subframes which are tobe shortened subframes (e.g., those where PUSCH transmission in symbolposition #13 is not allowed). For the case in which the network alsodetermines that an SRS transmission is needed from this UE the networkwill further determine or choose in which of the scheduled shortened ULsubframes the UE should transmit this SRS. As noted above, this isreferred to as the nth shortened UL subframe and so at this step thenetwork determines the value for n. If in the deployed embodiment the UEis to perform a modulo operation on the signaled value x then thenetwork determines x according to n=mod(x, number of UL subframes wherePUSCH transmission in symbol #13 is not allowed). Else if in thedeployed embodiment the UE is not going to use any modulo operation thenthe network determines x as n=x where x directly identifies the exactshortened UL subframe relative to the other granted shortened ULsubframes. These are of course two specific but non-limiting examples.One advantage of the modulo operation is that it enables theapplicability of more than one SRS parameter set in case only a smallnumber of shortened UL subframes are scheduled, as is detailed belowwith respect to FIG. 3.

Now knowing x, the network selects the SRS parameter set thatcorresponds to it (e.g., the SRS parameter set that includes the valuefor parameter x that matches the value for x found by the network asabove). The network completes its actions by transmitting amulti-subframe UL grant to the UE that includes an indication of thescheduled shortened UL subframes (where PUSCH transmission in symbol #13is not allowed) and an indication of the selected SRS parameter set. Solong as the UE transmits as instructed the network will then receive theSRS from the UE based on the combination of the indicated SRS parameterset and the indication of the scheduled UL subframes where PUSCHtransmission in symbol #13 is not allowed.

The above described method from the network's perspective can alsorepresent functions executed by computer code of a software programtangibly stored on a computer readable memory for implementing theseteachings, or functions to control operation of a radio access node 20as performed by one or more processors in cooperation with one or morecomputer readable memories storing software computer code.

Now consider a specific example which FIGS. 2 and 3 illustrate certaindifferences between the embodiments in which n=x and n=mod(x, number ofUL subframes where PUSCH transmission in symbol #13 is not allowed),respectively. The non-modulo operation illustrated at FIG. 2 will beconsidered a first embodiment and the modulo operation illustrated atFIG. 3 will be considered a second embodiment. In this example thenetwork configures the UE with 3 SRS parameter sets, and the networksends to the UE a single grant of resources that allocates 4 ULsubframes beginning at subframe #M.

In this example the three SRS parameter sets configured to the UE 10 areas follows:

-   -   Set 1: Generic SRS parameter set 1 (IFDMA-comb1, cyclic shift1,        etc.) including parameter x indicating SRS transmission in the        1^(st) shortened PUSCH subframe (x=1)    -   Set 2: Generic SRS parameter set 2 (IFDMA-comb2, cyclic shift2,        etc.) including parameter x indicating SRS transmission in the        2^(nd) shortened PUSCH subframe (x=2)    -   Set 3: Generic SRS parameter set 3 (IFDMA-comb3, cyclic shift3,        etc.) including parameter x indicating SRS transmission in the        3^(rd) shortened PUSCH subframe (x=3)

The different SRS parameter sets can use the same parameter values to acertain extent; it is sufficient that each set deviates from others byat least one parameter value.

In the case when the UE is configured to transmit SRS from multipleantenna ports, SRS transmission parameters for each antenna port may beimplicitly derived from the one set-specific cyclic shift and comb valuewhich are explicitly configured via RRC signaling. Alternatively theantenna ports may be explicitly configured by the network (for examplevia RRC signaling) for each SRS parameter set and each antenna port.

Further in this example, of the four UL subframes allocated by thesingle multi-subframe grant there are exactly two shortened subframes,those in which PUSCH transmission in symbol #13 is not allowed. Theseshortened subframes are subframes M and M+2, and these are specificallyidentified in the LTL multi-subframe grant itself.

For the first embodiment at FIG. 2, assume the SRS parameter set 2 aboveis signaled to the UE using a bit-value “10”. With no modulo operationin this embodiment n=x, and in the SRS parameter set 2 the value for xis 2. Since the specific UL subframe for SRS is n and in this firstembodiment n=x, it is the 2^(nd) subframe where PUSCH transmission insymbol#13 is not allowed where the UE is to send its SRS. In thisexample that specific subframe is subframe M+2. If we assume that thegrant allocates 4 consecutive UL subframes M, M+1, M+2 and M+3, thensubframe M+2 is the third scheduled UL subframe but still it is only thesecond shortened UL subframe that is allocated by the grant, and it isthe shortened UL subframes that the value of n counts.

This is shown at FIG. 2 in which there are a total of k=4 UL subframesallocated by the grant, subframes M and M+2 are the only shortenedsubframes (thus there are 2 shortened UL subframes allocated to the UEby the grant), and parameter set 2 with the relative timing indicationx=2 above identifies the second of these shortened subframes (since n=xin this first embodiment) as the one in which the UE is to transmit SRS(and also an A-CSI report and/or block ACK/NACK if the scheduling grantfurther requested it). For this FIG. 2 example the UE will transmit itsSRS in PUSCH UL subframe M+2 using further parameters defined in theentire SRS parameter set 2 above, namely IFDMA-comb2, cyclic shift2,etc. In other adaptations/variations of this SRS example, the UE willalso send in PUSCH UL subframe M+2 whichever feedback (A-CSI and/orblock ACK/NACK) report is/are triggered by the same resource grant thattriggered the SRS.

The determination of the subframe M+2 for the UE's SRS transmissionutilizes a combination signaling principle because it takes bothdynamically signaled indications into account; the scheduling allocationof UL subframes (of which one or more of them are shortened) as well asthe selected SRS parameter set which only selects a specific subframe ona relative basis in view of the overall UL grant that includes xshortened UL subframes.

For the second embodiment at FIG. 3, assume the SRS parameter set 3above is signaled to the UE using a bit-value “11”. With the modulooperation in this embodiment n=mod(x, number of UL subframes where PUSCHtransmission in symbol #13 is not allowed), and in the SRS parameter set3 the value for the relative timing indication x=3 and there are a totalof two shortened UL subframes in the grant. Therefore the subframe inwhich the UE is to transmit SRS is given by n=mod(x=3, 2) which yields avalue of n=1.

As above and as shown in FIG. 3, the k=4 allocated UL subframes are M,M+1, M+2 and M+3 and of these only M and M+2 are shortened. The value ofn identifies which of these shortened subframes is the one in which theUE is to send SRS, and FIG. 3 illustrates the SRS is transmitted insubframe M. For this FIG. 3 example the UE will transmit its SRS inPUSCH UL subframe M using the entire SRS parameter set 3 above, namelyIFDMA-comb3, cyclic shift3, etc. In other adaptations/variations of thisSRS example, the UE will also send in PUSCH UL subframe M whicheverfeedback (A-CSI and/or block ACK/NACK) report is/are triggered by thesame resource grant that triggered the SRS.

Due to the applied modulo operation in this second embodiment, for thisexample having only having 2 shortened PUSCH subframes in the grant theeNB/radio access node 20 can, to trigger SRS in the n=1^(st) subframewhere PUSCH in subframe #13 is not allowed, choose from two SRSparameter sets which each yield the same result n=mod(x,2)=1. Namely,the eNB can choose SRS parameter set 1 using (IFDMA-comb1, cyclicshift1, etc.) or it can choose SRS parameter set 3 using (IFDMA-comb3,cyclic shift3, etc.), either choice will yield n=mod(x,2)=1. This willincrease the flexibility for the eNB/radio access node 20 for SRStransmission without increasing the related signalling overhead.

In certain scenarios the eNB may want use a shortened subframe that canpossibly be used for an SRS transmission for providing extra time for aListen Before Talk (LBT) procedure. LBT is a common technique to avoidinterference on unlicensed spectrum because there may be other mobiledevices on the same spectrum that are not affiliated with the eNB, orthat are sending an initial transmission to associate with it, so forexample the eNB may wait some LBT period of time before transmitting. Inthis case the eNB would not trigger any SRS in the last subframe of anUL transmission burst. Instead, the eNB would reserve an empty SRSsymbol to ensure that there is sufficient time for the eNB's LBT periodat the end of an UL transmission burst that the eNB scheduled so thatthe eNB can start the next DL transmission burst at the subframeboundary. The eNB may take this kind of operation into account whenconfiguring SRS parameter sets by minimizing the number of SRS sets inwhich n selects a last subframe of the UL transmission burst scheduledby the eNB's grant of multiple UL subframes.

One technical effect of implementing embodiments of these teachings isthat they allow for a compact SRS request with multi-subframe grantsenabling different generic SRS parameter sets (IFDMA-comb, cyclic shift,etc.), and at the same time allowing the network to choose the specificsubframe for SRS transmission without sacrificing much away from totalflexibility. For example, in the case of a single UL subframe wherePUSCH transmission in symbol #13 is not allowed, all 3 different genericSRS parameter sets (IFDMA-comb x, cyclic shift x, etc.) can be freelychosen for the second embodiment that utilizes a modulo operationbecause n=mod(x,1) leads n=1 regardless of the value for x in thedifferent SRS parameter sets.

Contrasting against a separate parameter set and timing indication, theDCI overhead can be reduced dramatically by these teachings; for exampleonly 2 bits instead of ceiling(log₂(N))+2 bits (where N subframes can bescheduled from a single UL multi-subframe grant). In this case 2 bitsidentify one set of SRS parameters (IFDMA-comb, cyclic shift, etc.) andthere are ceiling(log₂(N)) bits for the time location of the SRStransmission (assuming as in the above non-limiting examples that theseceiling(log₂(N)) timing bits are totally independent of the indicationof PUSCH ending with symbol 12).

Embodiments of these teachings further enables a flexible utilization ofSRS resources while minimizing the SRS overhead. For example, the numberof SRS symbols within a UL transmission burst can be adjusteddynamically based on the number of UEs transmitting SRS.

Above the concept of signaling block ACK/NACK and triggering it arediscussed in the context of eLAA and MulteFire on unlicensed spectrum.Block ACK/NACK in these contexts is a part of these teachings. In LTEoperation with licensed band UL SCells, HARQ-ACK feedback followsdeterministic/predetermined timing where the HARQ-ACKs for PDSCH TBs arecarried in the first available UL subframe no earlier than in subframeHowever, with HARQ-ACK transmission on eLAA SCells subject toListen-Before-Talk requirements, the channel access mechanisms bringuncertainty to the availability of HARQ-feedback channel (PUCCH orPUSCH) at a given point in time. Because of this, eLAA operation cannotrely on predetermined HARQ-ACK timing, and mechanism(s) to cope withunexpected delays in HARQ-ACK feedback are needed. The block ACK/NACKtechnique disclosed herein is such a mechanism.

While the scenario where LBT procedure affects HARQ-ACK feedback is newto LTE, similar considerations have taken place in the context of othertechnologies used in unlicensed spectrum. As an example Wi-Fi (namely802.11e/n) supports a mechanism called Block Acknowledgement, where onestation may request another to provide acknowledgements for severalframes using a bitmap [2]. Similar approach seems useful and necessaryalso in eLAA, particularly as it allows for keeping all theHARQ-feedback on the unlicensed carriers even if UL transmission need tobe suspended from time to time due to LBT.

In the context of LTE, and given the uncertainty in the timing forHARQ-ACK feedback, it is natural to relate the Block-ACK directly toHARQ-processes rather than subframes. This help in avoiding ambiguitythat the LBT requirements along with very flexible UL-DL“configurations” inevitably creates. As for the triggering mechanismitself; the straightforward solution is to re-use the Aperiodic CSItriggering principles, with 2-3 bits in the UL grant indicating thecarriers for which Block-ACK should be reported using PUSCH. This allowsfor managing the overhead associated with HARQ-ACK feedback bytriggering feedback for only some of the carriers. The resourceallocation as well as channel coding principles can be directly borrowedfrom A-CSI framework.

FIG: 4A is a process flow diagram that summarizes some of the aboveaspects from the perspective of the UE 10 or other mobile device. FIG.4A details a method for transmitting a reference signal or channel stateinformation (CSI) report. In this summary at block 402 the UE receives aconfiguration of multiple parameter sets each set including a timingindication; the parameter x in the above examples is such a timingindication. Then at block 404 the UE receives a grant (e.g., a PDCCH)that allocates multiple uplink subframes (e.g., PUSCHs) of which atleast some may be shortened such that uplink transmission is prohibitedin only a portion thereof In an embodiment, if none of the subframes isshortened on the last symbol of subframe, and SRS is triggered, it ispossible to use this combination to trigger SRS in UpPTS part of the ULtransmission burst, i.e. in the DL partial ending subframe. Whenfollowing this option, SRS triggering can follow parameters defined bythe corresponding SRS parameter set. The only difference is that timingindication and parameter x is interpreted in a specific way. In otherwords, if none of the subframes is shortened on the last symbol ofsubframe, and SRS is triggered, UE will transmit SRS in the last symbolof subframe preceding the first scheduled uplink subframe. In the aboveexamples those shortened UL subframes were those for which PUSCHtransmissions in symbol position #13 were prohibited (that is, thesesubframes effectively ended at symbol position #12, unless the UE was totransmit an SRS in symbol position #13). Block 406 summarizes that basedon the grant the UE determines which of the multiple uplink subframesare shortened; at block 408 the UE determines from the grant that areference signal and/or CSI report is requested; and at block 410 the UEdetermines from the grant a selected one of the multiple parameter sets.Now at block 412 the UE identifies one uplink subframe from among themultiple uplink subframes based on the determination which of themultiple allocated uplink subframes are shortened. If there is at leastone shortened subframe in the allocation then the UE will use the timingindication from the selected parameter set (in the above examples thatwas given by n=x, or by performing a modulo operation on x to resolvethe value of n) to identify the one uplink subframe. If instead thereare no such shortened subframes then this fact identifies the uplinksubframe as the one preceding all of those UL subframes in themulti-subframe allocation. Finally at block 414 the UE transmits thereference signal and/or the CSI report, per the grant's request at block408, in the identified uplink subframe.

FIG. 4A also sets forth actions performed by a device such as a UE orone or more components thereof, as well as functions done by such a UEas controlled by a tangibly embodied computer software program when sucha program is executed by one or more processors of the UE.

FIG. 4B is a process flow diagram that summarizes some of the aboveaspects from the perspective of the eNB or other network radio accessnode 20. FIG. 4B details a method for triggering transmission of areference signal and/or a channel state information (CSI) report. Thetriggering is done by the eNB/radio access node and the UE is the entitythat is triggered to transmit. In this summary at block 452 the eNBtransmits to a UE a configuration of multiple parameter sets each setincluding a timing indication. The eNB determines at block 454 multipleuplink subframes that are to be scheduled to a UE. At least some ofthese multiple uplink subframes may be shortened such that uplinktransmission is prohibited in only a portion thereof, as detailed abovewith numerous examples. The eNB further at block 456 identifies oneshortened uplink subframe; this is the one subframe in which the UE isto transmit a reference signal and/or a CSI report and/or blockACK/NACK. The eNB then selects one of the multiple parameter sets atblock 458. If at least one of the multiple uplink subframes is shortenedthen the parameter set is selected such that the corresponding timingindication indicates the identified one uplink subframe from among themultiple uplink subframes, and in the above examples this identifieduplink subframe is always a shortened uplink subframe. This selection isfor the value of n in the above examples, and since the timingindication gives the value of x this selection is highly dependent onwhether the embodiment utilizes n=x or n=some modulo function on x (orother implementations). eNB may take into account also other UEs whenassigning SRS parameter sets for an UE. It may also provide orthogonalSRS resources for all UEs triggered to send SRS during multi-subframescheduling period of k subframes. The number of UEs triggered to sendSRS during those k subframes may also impact eNB's decision how manyshortened subframes it allocates during multi-subframe scheduling periodof k subframes. For the case in which none of the multiple uplinksubframes scheduled for the UE are shortened, then that fact points to aspecific uplink frame preceding all of those multiple subframes as theone that is identified at block 456 for the UE to transmit its SRSand/or A-CSI and/or block ACK/NACK. Finally at block 460 the eNBtransmits to the UE a grant that schedules the UE for the multipleuplink subframes and that triggers the UE to transmit a reference signaland/or a CSI report, the grant further identifying the selectedparameter set and which of the multiple uplink subframes are shortened.

FIG. 4B also sets forth actions performed by a communication device suchas a radio access node such as an eNB or one or more components thereof,as well as functions done by such an access node as controlled by atangibly embodied computer software program when such a program isexecuted by one or more processors of that same access node.

FIG. 5 is a schematic diagram illustrating some components of theeNB/radio access node 20 and the UE 10 shown at FIG. 1. In the wirelesssystem/cell a wireless network is adapted for communication over awireless link 11 with an apparatus such as a mobile communication devicewhich may be referred to as a UE 10, via a radio network access nodesuch as a Node B (base station), and more specifically an eNB 20. Thenetwork may include a network control element (NCE, not shown) that mayinclude mobility management entity/serving gateway (MME/S-GW)functionality, and which provides connectivity with a further networksuch as a telephone network and/or a data communications network (e.g.,the internet).

The UE 10 includes a controller, such as a computer or a data processor(DP) 10D, a computer-readable memory medium embodied as a memory (MEM)10B that stores a program of computer instructions (PROG) 10C, and asuitable wireless interface, such as radio frequency (RF)transmitter/receiver combination 10D for bidirectional wirelesscommunications with the eNB 20 via one or more antennas.

The wireless link between the UE 10 and the eNB 20 can be measured forlink quality (for example, received signal strength or quality) and thisinformation is what is included in the A-CSI report that may betriggered according to the above teachings. Further, the UE 10 typicallyincludes a galvanic power supply (or other portable power supply), itmay have multiple antennas beyond only the single antenna shown, and theMEM 10B and DP 10A may be implemented as multiple distinct physicalentities that operate in practice as a single unit, and it may havemultiple distinct radios or one or more software-defined radios forcommunicating on different spectrum and using different radio accesstechnologies.

The eNB 20 also includes a controller, such as a computer or a dataprocessor (DP) 20A, a computer-readable memory medium embodied as amemory (MEM) 20B that stores a program of computer instructions (PROG)20C, and a suitable wireless interface, such as RF transmitter/receivercombination 20D for communication with the UE 10 (as well as other UBs)via one or more antennas. The eNB 20 is coupled via a data/control path(not shown) to the NCE and this path may be implemented as an interface.The eNB 20 may also be coupled to another eNB via another data/controlpath, which may be implemented as a different interface. The eNB 20typically has multiple antennas beyond only the single antenna shown,multiple distinct radios which may or may not include software-definedradios for communicating on different spectrum and using different radioaccess technologies, and like the UE 10 the MEM 20B and DP 20A of theeNB 20 may be implemented as multiple distinct physical entities thatoperate in practice as a single unit.

At least one of the PROGs 10C/20C is assumed to include programinstructions that, when executed by the associated DP 10A/20A, enablethe device to operate in accordance with exemplary embodiments of thisinvention as detailed above. That is, various exemplary embodiments ofthis invention may be implemented at least in part by computer softwareexecutable by the DP 10A of the UE 10; by the DP 20A of the eNB 20, orby hardware or by a combination of software and hardware (and firmware).

In various exemplary embodiments the UE 10 and/or the eNB 20 may alsoinclude dedicated processors, for example a RRC module, a RF front end,and the like. There may also be one or more modules that is/areconstructed so as to operate in accordance with various exemplaryembodiments of these teachings.

The computer readable MEMs 10B/20B may be of any type suitable to thelocal technical environment and may be implemented using any one or moresuitable data storage technology, such as semiconductor based memorydevices, flash memory, magnetic memory devices and systems, opticalmemory devices and systems, fixed memory and removable memory,electromagnetic, infrared, or semiconductor systems. Following is anon-exhaustive list of more specific examples of the computer readablestorage medium/memory: an electrical connection having one or morewires, a portable computer diskette, a hard disk, a random access memory(RAM), a read-only memory (ROM), an erasable programmable read-onlymemory (EPROM or Flash memory), an optical fiber, a portable compactdisc read-only memory (CD-ROM), an optical storage device, a magneticstorage device, or any suitable combination of the foregoing.

The DPs 10A/20A may be of any type suitable to the local technicalenvironment, and may include one or more of general purpose computers,special purpose computers, microprocessors, digital signal processors(DSPs) and processors based on a multicore processor architecture, asnon-limiting examples. The wireless interfaces (e.g., the radios10D/20D) may be of any type suitable to the local technical environmentand may be implemented using any suitable communication technology suchas individual transmitters, receivers, transceivers or a combination ofsuch components.

In general, the various embodiments of the UE 10 can include, but arenot limited to, smart phones, machine-to-machine (M2M) communicationdevices, cellular telephones, personal digital assistants (PDAs) havingwireless communication capabilities, portable computers having wirelesscommunication capabilities, image capture devices such as digitalcameras having wireless communication capabilities, gaming deviceshaving wireless communication capabilities, music storage and playbackappliances having wireless communication capabilities, Internetappliances permitting wireless Internet access and browsing, as well asportable units or terminals that incorporate combinations of suchfunctions. Any of these may be embodied as a hand-portable device, awearable device, a device that is implanted in whole or in part, avehicle-mounted communication device, and the like.

It should be understood that the foregoing description is onlyillustrative. Various alternatives and modifications can be devised bythose skilled in the art. For example, features recited in the variousdependent claims could be combined with each other in any suitablecombination(s). In addition, features from different embodimentsdescribed above could be selectively combined into an embodiment that isnot specifically detailed herein as separate from the others.Accordingly, the description is intended to embrace all suchalternatives, modifications and variances which fall within the scope ofthe appended claims.

The following abbreviations that may be found in the specificationand/or the drawing figures are defined as follows:

-   -   3GPP Third Generation Partnership Project    -   ACK Acknowledgement    -   CSI Channel State information    -   DCI Downlink Control Information    -   DL Downlink    -   eLAA Enhanced Licensed Assisted Access    -   eNB Evolved NodeB    -   ETSI European Telecommunications Standards Institute    -   FDD Frequency Division Duplex    -   FS2 Frame Structure 2 (frame structure for LTE TDD)    -   HARQ Hybrid Automatic Repeat reQuest    -   IFDMA Interleaved Frequency Domain Multiple Access    -   LAA Licensed Assisted Access    -   LBT Listen-Before-Talk    -   LTE Long Term Evolution    -   NACK Negative ACK    -   OFDM Orthogonal Frequency Domain Multiplexing    -   PCell Primary cell    -   PDCCH Physical Downlink Control Channel    -   PRB Physical Resource Block    -   PUCCH Physical Uplink Control Channel    -   PUSCH Physical Uplink Shared Channel    -   TB Transport Block    -   TM Transmission Mode    -   SCell Secondary cell    -   SRS Sounding reference signal    -   TDD Time Division Duplex    -   UE UE Equipment    -   UL Uplink

1. A method for transmitting a reference signal and/or a channel stateinformation (CST) report and/or a block acknowledgement, the methodcomprising: receiving a configuration of multiple parameter sets eachset including a timing indication; receiving a grant that allocatesmultiple uplink subframes; based on the grant, determining which of themultiple allocated uplink subframes are shortened such that uplinktransmission is prohibited in only a portion thereof; determining fromthe grant that a reference signal and/or CSI report and/or blockacknowledgement is requested; determining from the grant a selected oneof the multiple parameter sets; identifying one uplink subframe based onthe determination which of the multiple allocated uplink subframes areshortened; and transmitting the reference signal and/or the CSI reportand/or block acknowledgement as requested by the grant in the identifieduplink subframe.
 2. The method according to claim 1, wherein for thecase in which it is determined that none of the multiple allocateduplink subframes are shortened, the identified uplink subframeimmediately precedes all of the multiple allocated uplink subframes. 3.The method according to claim 1, wherein at least one of the multipleallocated uplink subframes is determined to be shortened, and theidentified one uplink subframe is identified from among only themultiple allocated uplink subframes that are shortened using the timingindication from the selected parameter set.
 4. The method according toclaim 3, wherein the timing indication in each of the parameter setsindicates subframe timing relative to the multiple allocated uplinksubframes.
 5. The method according to claim 4, wherein identifying theone uplink subframe comprises counting among only the shortened uplinksubframes a number of subframes equal to a value of the timingindication from the selected parameter set.
 6. The method according toclaim 4, wherein identifying the one uplink subframe comprises countingamong only the shortened uplink subframes a number of subframes equal tothe result of a modulo operation on a value of the timing indicationfrom the selected parameter set and a total number of only shorteneduplink frames among the multiple uplink frames. 7.-10. (canceled)
 11. Anapparatus comprising: at least one processor; and at least one memorystoring computer program code; wherein the at least one processor isconfigured with the at least one memory and the computer program code tocause a user equipment (UE) to transmit a reference signal and/or a orchannel state information (CST) report and/or a block acknowledgement bycausing the UE to at least: in response to receiving a configuration ofmultiple parameter sets each set including a timing indication and agrant that allocates multiple uplink subframes, determine based on thegrant which of the multiple allocated uplink subframes are shortenedsuch that uplink transmission is prohibited in only a portion thereof;determine from the grant that a reference signal and/or CSI reportand/or block acknowledgement is requested; determine from the grant aselected one of the multiple parameter sets; identify one uplinksubframe based on the determination which of the multiple allocateduplink subframes are shortened; and transmit the reference signal and/orthe CSI report and/or block acknowledgement as requested by the grant inthe identified uplink subframe.
 12. The apparatus according to claim 11,wherein for the case in which it is determined that none of the multipleallocated uplink subframes are shortened, the identified uplink subframeprecedes all of the multiple allocated uplink subframes.
 13. Theapparatus according to claim 11, wherein at least one of the multipleallocated uplink subframes is determined to be shortened, and theidentified one uplink subframe is identified from among only themultiple allocated uplink subframes that are shortened using the timingindication from the selected parameter set.
 14. The apparatus accordingto claim 13, wherein the timing indication in each of the parameter setsindicates subframe timing relative to the multiple allocated uplinksubframes.
 15. The apparatus according to claim 14, wherein identifyingthe one uplink subframe comprises counting among only the shorteneduplink subframes a number of subframes equal to a value of the timingindication from the selected parameter set.
 16. The apparatus accordingto claim 14, wherein identifying the one uplink subframe comprisescounting among only the shortened uplink subframes a number of subframesequal to the result of a modulo operation on a value of the timingindication from the selected parameter set and a total number of onlyshortened uplink frames among the multiple uplink frames.
 17. Theapparatus according to claim 11, wherein the reference signal and/or theCSI report and/or block acknowledgement is transmitted from one or moreantenna ports that is/are identified by the selected one of the multipleparameter sets.
 18. The apparatus according to claim 11, wherein theselected one of the multiple parameter sets is determined from a valueof exactly 2 bits in the grant.
 19. The apparatus according to claim 11,wherein the method is performed by a user equipment which transmits thereference signal and/or the CSI report and/or block acknowledgement onunlicensed radio spectrum.
 20. A method for triggering transmission of areference signal and/or a channel state information (CSI) report and/ora block acknowledgement, the method comprising: transmitting to a userequipment (UE) a configuration of multiple parameter sets each setincluding a timing indication; determining multiple uplink subframes tobe scheduled to a UE; identifying one uplink subframe in which the UE isto transmit a reference signal and/or a CSI report and/or blockacknowledgement; selecting one of the multiple parameter sets, whereinfor the case in which at least one of the multiple uplink subframes isshortened such that uplink transmission is prohibited in only a portionthereof the timing indication of the selected parameter set indicatesthe identified one uplink subframe from among the multiple uplinksubframes; and transmitting to the UE a grant that schedules the UE forthe multiple uplink subframes and that triggers the UE to transmit areference signal and/or a CSI report and/or block acknowledgement, thegrant further identifying the selected parameter set and which if any ofthe multiple uplink subframes are shortened.
 21. (canceled)
 22. Themethod according to claim 20, wherein the grant identifies that at leastone of the multiple allocated uplink subframes is shortened, and thetiming indication in each of the parameter sets indicates subframetiming relative to the multiple uplink subframes, and the timingindication of the selected parameter set along with the grant indicatesthe identified one uplink subframe. 23.-29. (canceled)
 30. An apparatuscomprising: at least one processor; and at least one memory storingcomputer program code; wherein the at least one processor is configuredwith the at least one memory and the computer program code to cause aradio access node to trigger transmission of a reference signal and/or achannel state information (CSI) report and/or a block acknowledgement bycausing the radio access node to at least: transmit to a user equipment(UE) a configuration of multiple parameter sets each set including atiming indication; determine multiple uplink subframes to be scheduledto a UE; identify one uplink subframe in which the UE is to transmit areference signal and/or a CSI report and/or block acknowledgement;select one of the multiple parameter sets, wherein for the case in whichat least one of the multiple uplink subframes is shortened such thatuplink transmission is prohibited in only a portion thereof the timingindication of the selected parameter set indicates the identified oneuplink subframe; and transmit to the UE a grant that schedules the UEfor the multiple uplink subframes and that triggers the UE to transmit areference signal and/or a CSI report and/or block acknowledgement, thegrant further identifying the selected parameter set and which if any ofthe multiple uplink subframes are shortened.
 31. The apparatus accordingto claim 30, wherein for the case in which the grant identifies thatnone of the multiple allocated uplink subframes are shortened, theidentified uplink subframe precedes all of the multiple allocated uplinksubframes.
 32. The apparatus according to claim 30, wherein the grantidentifies that at least one of the multiple allocated uplink subframesis shortened.
 33. The apparatus according to claim 32, wherein thetiming indication in each of the parameter sets indicates subframetiming relative to the multiple uplink subframes, and the timingindication of the selected parameter set along with the grant indicatesthe identified one uplink subframe.
 34. The apparatus according to claim33, wherein selecting the one of the multiple parameter sets comprisesselecting one of the parameter sets for which a value of thecorresponding timing indication equals a count among only the shorteneduplink subframes to the identified one uplink subframe which is ashortened uplink subframe.
 35. The apparatus according to claim 33,wherein selecting the one of the multiple parameter sets comprisesselecting one of the parameter sets for which a result of a modulooperation on a value of the corresponding timing indication and a totalnumber of only shortened uplink frames among the multiple uplink framesequals a count among only the shortened uplink subframes to theidentified one uplink subframe which is a shortened uplink subframe. 36.The apparatus according to claim 30, wherein selected one of themultiple parameter sets identifies one or more antenna ports of the UEfrom which the reference signal and/or the CSI report and/or blockacknowledgement is to be transmitted.
 37. The apparatus according toclaim 30, wherein the grant identifies the selected parameter set usingexactly 2 bits.
 38. The apparatus according to claim 30, wherein themethod is performed by a radio access node which transmits the grant onunlicensed radio spectrum.